Cheng Yongmao, the engineer in charge of the reconstruction project on the Jiankou section of the Great Wall, looks as the sun rises over the wall, located in Huairou District, north of Beijing, China, June 7, 2017. DAMIR SAGOLJ/REUTERS

A cameraman documenting the reconstruction project of the Jiankou section of the Great Wall, films as the sun rises over the wall, located in Huairou District, north of Beijing, China, June 7, 2017. DAMIR SAGOLJ/REUTERS

A man walks behind a mule carrying bricks up the steep path towards the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. "The path is too steep and the mountains are too high, so bricks can only be transported by mules," said local mule owner Cao Xinhua. DAMIR SAGOLJ/REUTERS

Mules carry bricks and other construction material up the steep path towards the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. "The path is too steep and the mountains are too high, so bricks can only be transported by mules," said local mule owner Cao Xinhua. DAMIR SAGOLJ/REUTERS

A worker unloads bricks from mules at the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. "The path is too steep and the mountains are too high, so bricks can only be transported by mules," said local mule owner Cao Xinhua. DAMIR SAGOLJ/REUTERS

A mule decorated with red tassels carries bricks and other construction materials up the steep path towards the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. "The path is too steep and the mountains are too high, so bricks can only be transported by mules," said local mule owner Cao Xinhua. DAMIR SAGOLJ/REUTERS

A worker waits for bricks and other construction materials to be delivered on the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. DAMIR SAGOLJ/REUTERS

People wait for bricks and other equipment to be delivered as they work on the reconstruction of the Jiankou section of the Great Wall, located in Huairou District, north of Beijing, China, June 7, 2017. DAMIR SAGOLJ/REUTERS